The starting gun has been fired on a Labour leadership election , with Andy Burnham seeking a return to Westminster and Wes Streeting quitting the cabinet and indicating he will run in any contest. Speculation that Sir Keir could face a challenge has been circling for months, but after days of mounting calls for him to resign following the disastrous Labour election results, candidates have finally begun to make their moves . Mr Streeting, Mr Burnham and deputy prime minister Angela Rayner have all been widely touted as the most probable challengers to Sir Keir’s premiership, while Al Carns and Ed Miliband have also been named as potential candidates. On Thursday, Ms Rayner made her clearest indication yet by announcing she had been cleared of deliberate wrongdoing in an investigation over her tax affairs, which had previously been seen as a major political barrier.…